This is a thesis I'm working through in my head, so I wanted to document my thoughts and revisit it later. I think I have just four categories of apps on my smartphone and tablet, with the primary differentiator being the manner in which I access those apps:

Apps primarily accessed through the icon

Apps primarily accessed through notifications

Apps accessed about 50/50 through the icon and notifications

Apps that I never access at all

Obviously, nobody wants to be in category #4, but is there a 'best' category to be in, and if so which is it?

Apps in category #1 tend to be media, content consumption, games, and utilities. My engagement with apps in this category is bifurcated. There are the apps on my home screen that I use daily (if not hourly), such as Safari, RSS reader and read it later apps, podcasts, camera/photos, and weather. Then there are apps that I rarely use but won't consider deleting, such as Netflix, watchESPN, banking, utilities, content creation, shopping, etc.

Apps in category #2 are typically buried in a folder somewhere, but I still value their content. I like getting alerts of breaking news, a new clip discussing my favorite sports teams, new concerts in my area, and IFTTT triggers. This category also includes social networking apps that I don't use much, such as LinkedIn, Facebook Messenger, and Google Hangouts. Naturally, I only engage with these apps when I get a notification worth opening, which is rare. With news apps, the headlines usually suffice, and with messaging apps it's usually someone I don't know very well (otherwise they'd text or email me). Overall, my engagement with these apps is very low, but I don't want to delete them and miss their notifications either.

Apps in category #3 tend to be more social in nature, such as Messages, FaceTime, email, Instagram, etc. It also includes things like sports score/news apps and fantasy football. I don't play many mobile games or use Twitter a lot, but I'd guess they would fit this category for many users. My engagement level with this group of apps has the highest overall average.

If the app developer's business model depends on high engagement, then category #3 is clearly where to be (at least according to my usage habits). That doesn't mean every app needs to have a social component to it, though. I think a lot of apps in category #1 (and perhaps #4) could have more relevant and engaging notifications. For example: top new and expiring titles on Netflix and other media apps (Spotify already does a good job of this), new articles from select feeds in my RSS reader, or custom-tailored deals from the Amazon app. Even something as simple as a weather app could be enhanced with intelligent notifications based on location and the user's settings.

This isn't a once-size-fits-all approach to improving mobile app engagement, but I find it useful to categorize apps in this way. Quality and quantity of notifications must be balanced delicately. Once I turn off notifications for an app I rarely go back. Engagement goals should also be considered in the context of the app's business model. A banking app that provides a steady stream of financial tips and alerts may be more annoying than useful and overshadow important notifications. Conversely, a social networking app with inferior notifications may be deemed useless.